1. Field of the Invention
The present invention relates to a semiconductor unit, a cooling device used in the unit, and manufacturing methods for the semiconductor unit and the cooling device. In particular, the present invention relates to a semiconductor unit including a substrate loaded with a plurality of semiconductor components, a cooling device used in the unit provided above the components, and manufacturing methods of both the semiconductor unit and the cooling device.
2. Description of the Related Art
To realize high-density mounting of a plurality of semiconductor components in a semiconductor unit with MultiChip Module (MCM), it is a common practice to create many bumps (connecting terminals) on nearly the whole connecting surface of the semiconductor components and then load the semiconductor components on the substrate.
In this case, since the semiconductor components are high-density mounted, heat generated in each semiconductor component becomes relatively high. Therefore, it is required to efficiently radiate the heat.
In order to radiate the heat, conventionally, for example, a method of collectively covering the exposed surface of each semiconductor component with a metallic cooling member is used. In the case of air cooling the cooling member so that heat is conducted away from the semiconductor component, the cooling is done through ventilation by placing many fins on the cooling member. On the other hand, when a more efficient method of radiation is required, liquid cooling is typically performed by circulating coolant inside the cooling member. In general, compared to the air cooling, in the case of the liquid cooling, the expense for the cooling member becomes costly and also miniaturization of the cooling member is prevented.
In either case of implementing the above-mentioned air cooling method or the liquid cooling method, it is necessary to closely connect the semiconductor component, which is the generator of the heat, with the cooling member so as to attain a thermal conduction between the two, in order to efficiently radiate the heat. However, it is not easy to attain a good adhesion by simply connecting the semiconductor component with the cooling member.
Therefore, in order to eliminate any clearance between the semiconductor component and the cooling member that may cause a resistance to the heat transfer, it is in common practice to apply a thermally conductive compound on the exposed surface of the semiconductor component to connect the component with the cooling member. In this case, for example, the compound is applied individually to each semiconductor component with a syringe-like compound injection device by controlling the amount of the compound by injection pressure and injection time.
However, in the case of the method of applying the compound described above, it is tedious to evenly control the amount of the compound applied to each semiconductor component. Also if the amount of the compound is unevenly applied to an individual component, the adhesion between the semiconductor component and the cooling member may be inadequate. Further, it is necessary to adjust the amount of the compound applied to each component depending on dimensional differences between semiconductor components within the same lot or positional differences caused during assembling of the semiconductor components to the substrate, which adjustment is also tedious with the conventional method.
In addition, when the amount of the compound applied to the semiconductor component becomes excessive or the liquidity of the matrix component of the compound is too high, mainly the matrix component flows out from peripheral areas of the semiconductor component and stains the substrate and bumps. In this case, metal filler in the compound may cause a short circuit or malfunction of the semiconductor unit.
A general object of the present invention is to provide a semiconductor unit, a cooling device, and methods for both the semiconductor unit and cooling device in which the above disadvantages are eliminated.
Another and more specific object of the present invention is to provide a semiconductor unit including semiconductor components and a cooling member connected together to secure thermal conductivity which surpasses the related art in heat radiation and also has fewer problems such as short circuits which may be caused by compound stains, to provide a cooling device used in the semiconductor unit, and to provide suitable manufacturing methods for the semiconductor unit and the cooling device.
The above objects of the present invention are achieved by a semiconductor unit comprising: a substrate; a plurality of semiconductor components loaded on the substrate; and a cooling device comprising a first hole for injecting a compound to connect the cooling device with the semiconductor components.
The above objects of the present invention are also achieved by a cooling device comprising: a member thermally coupled with semiconductor components; and a first hole for injecting a compound to connect the cooling device with the semiconductor components.
The above objects of the present invention are also achieved by a manufacturing method for a semiconductor unit comprising a plurality of semiconductor components loaded on a substrate and a cooling device arranged above the semiconductor components, comprising steps of: (a)injecting a compound through an injection hole on the cooling device; (b)forming a compound layer in between the semiconductor component and the cooling device; and (c)connecting the semiconductor component with the cooling device by the compound layer.
The above-mentioned objects of the present invention are also achieved by a manufacturing method for a cooling device arranged above semiconductor components loaded on a substrate, comprising the steps of: forming an injection hole in a member of the cooling device for injecting a compound; and injecting the compound through the injection hole so that the semiconductor components and the member of the cooling device are fixed together.